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Human microglial cells synthesize albumin in brain.

Ahn SM, Byun K, Cho K, Kim JY, Yoo JS, Kim D, Paek SH, Kim SU, Simpson RJ, Lee B - PLoS ONE (2008)

Bottom Line: In a pilot phase study of Human Brain Proteome Project, we found evidence that microglial cells in brain may synthesize albumin.Furthermore, we demonstrate that the synthesis and secretion of albumin from microglial cells is enhanced upon microglial activation by Abeta(1-42)- or lipopolysaccharide (LPS)-treatment.These data indicate that microglial cells may play a beneficial role in AD by secreting albumin that not only inhibits Abeta polymerization but also increases its clearance.

View Article: PubMed Central - PubMed

Affiliation: Center for Genomics and Proteomics, Lee Gil Ya Cancer and Diabetes Institute, Gachon University of Medicine and Science, Incheon, Korea.

ABSTRACT
Albumin, an abundant plasma protein with multifunctional properties, is mainly synthesized in the liver. Albumin has been implicated in Alzheimer's disease (AD) since it can bind to and transport amyloid beta (Abeta), the causative agent of AD; albumin is also a potent inhibitor of Abeta polymerization. Despite evidence of non-hepatic transcription of albumin in many tissues including kidney and pancreas, non-hepatic synthesis of albumin at the protein level has been rarely confirmed. In a pilot phase study of Human Brain Proteome Project, we found evidence that microglial cells in brain may synthesize albumin. Here we report, for the first time, the de novo synthesis of albumin in human microglial cells in brain. Furthermore, we demonstrate that the synthesis and secretion of albumin from microglial cells is enhanced upon microglial activation by Abeta(1-42)- or lipopolysaccharide (LPS)-treatment. These data indicate that microglial cells may play a beneficial role in AD by secreting albumin that not only inhibits Abeta polymerization but also increases its clearance.

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Related in: MedlinePlus

Representative MS/MS spectra of a tryptic peptide of albumin.Peptide sequencing provided clear evidence that albumin found in HMO6 cells is not bovine but human origin. The peptide QNCELFEQLGEYK is human-specific (i.e. the sequence is not 100% homologous with its bovine homologue, and thus distinguishable using MS/MS. The list of tryptic peptides identified using MS/MS is summarized in Table S1. b and y represent b ions and y ions respectively, which are generated during peptide fragmentation in MS/MS [29].
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pone-0002829-g002: Representative MS/MS spectra of a tryptic peptide of albumin.Peptide sequencing provided clear evidence that albumin found in HMO6 cells is not bovine but human origin. The peptide QNCELFEQLGEYK is human-specific (i.e. the sequence is not 100% homologous with its bovine homologue, and thus distinguishable using MS/MS. The list of tryptic peptides identified using MS/MS is summarized in Table S1. b and y represent b ions and y ions respectively, which are generated during peptide fragmentation in MS/MS [29].

Mentions: To further confirm that albumin detected in HMO6 cells is not bovine albumin from the incubation media but human albumin, peptide sequencing using tandem mass spectrometry (MS/MS) was performed, which provided clear evidence that the albumin in HMO6 cells is human origin (Fig. 2). The list of tryptic peptides identified using MS/MS is summarized in Table S1.


Human microglial cells synthesize albumin in brain.

Ahn SM, Byun K, Cho K, Kim JY, Yoo JS, Kim D, Paek SH, Kim SU, Simpson RJ, Lee B - PLoS ONE (2008)

Representative MS/MS spectra of a tryptic peptide of albumin.Peptide sequencing provided clear evidence that albumin found in HMO6 cells is not bovine but human origin. The peptide QNCELFEQLGEYK is human-specific (i.e. the sequence is not 100% homologous with its bovine homologue, and thus distinguishable using MS/MS. The list of tryptic peptides identified using MS/MS is summarized in Table S1. b and y represent b ions and y ions respectively, which are generated during peptide fragmentation in MS/MS [29].
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2483733&req=5

pone-0002829-g002: Representative MS/MS spectra of a tryptic peptide of albumin.Peptide sequencing provided clear evidence that albumin found in HMO6 cells is not bovine but human origin. The peptide QNCELFEQLGEYK is human-specific (i.e. the sequence is not 100% homologous with its bovine homologue, and thus distinguishable using MS/MS. The list of tryptic peptides identified using MS/MS is summarized in Table S1. b and y represent b ions and y ions respectively, which are generated during peptide fragmentation in MS/MS [29].
Mentions: To further confirm that albumin detected in HMO6 cells is not bovine albumin from the incubation media but human albumin, peptide sequencing using tandem mass spectrometry (MS/MS) was performed, which provided clear evidence that the albumin in HMO6 cells is human origin (Fig. 2). The list of tryptic peptides identified using MS/MS is summarized in Table S1.

Bottom Line: In a pilot phase study of Human Brain Proteome Project, we found evidence that microglial cells in brain may synthesize albumin.Furthermore, we demonstrate that the synthesis and secretion of albumin from microglial cells is enhanced upon microglial activation by Abeta(1-42)- or lipopolysaccharide (LPS)-treatment.These data indicate that microglial cells may play a beneficial role in AD by secreting albumin that not only inhibits Abeta polymerization but also increases its clearance.

View Article: PubMed Central - PubMed

Affiliation: Center for Genomics and Proteomics, Lee Gil Ya Cancer and Diabetes Institute, Gachon University of Medicine and Science, Incheon, Korea.

ABSTRACT
Albumin, an abundant plasma protein with multifunctional properties, is mainly synthesized in the liver. Albumin has been implicated in Alzheimer's disease (AD) since it can bind to and transport amyloid beta (Abeta), the causative agent of AD; albumin is also a potent inhibitor of Abeta polymerization. Despite evidence of non-hepatic transcription of albumin in many tissues including kidney and pancreas, non-hepatic synthesis of albumin at the protein level has been rarely confirmed. In a pilot phase study of Human Brain Proteome Project, we found evidence that microglial cells in brain may synthesize albumin. Here we report, for the first time, the de novo synthesis of albumin in human microglial cells in brain. Furthermore, we demonstrate that the synthesis and secretion of albumin from microglial cells is enhanced upon microglial activation by Abeta(1-42)- or lipopolysaccharide (LPS)-treatment. These data indicate that microglial cells may play a beneficial role in AD by secreting albumin that not only inhibits Abeta polymerization but also increases its clearance.

Show MeSH
Related in: MedlinePlus